A few of us -- Sofia, especially -- have been waiting for the results from this European study of memantine (Namenda) in PDD and DLB. Though the sample size was small -- 72 patients total, divided between the Namenda group and the placebo group -- it was a well-designed study because it was double-blind (neither the patients nor the researchers knew which group they were in) and placebo-controlled.

"56 (78%) completed the study. All withdrawals were owing to adverse events, but the proportion of withdrawals was similar in both groups. At week 24 the patients in the memantine group had better CGIC [clinical global impression of change] scores than those taking placebo. With the exception of improved speed on attentional tasks in the memantine group (a quick test of cognition [AQT] form), there were no significant differences between the groups in secondary outcome measures."

My impression is that these are good findings but not the sort of improvement that has been seen in studies of DLB/PDD patients and AChEIs (Exelon, Aricept, Razadyne). If you have a different view, please share!

BACKGROUND: Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) are common forms of dementia that substantially affect quality of life. Currently, the only treatment licensed for PDD is rivastigmine, and there are no licensed treatments for DLB. We aimed to test the safety and efficacy of the N-methyl D-aspartate (NMDA) receptor antagonist memantine in patients with PDD or DLB.

METHODS: We did a parallel-group, 24-week, randomised controlled study of memantine (20 mg per day) versus placebo at four psychiatric and neurological outpatient clinics in Norway, Sweden, and the UK during 2005-08. Patients were included if they fulfilled the UK Parkinson's Disease Society Brain Bank clinical diagnostic criteria for Parkinson's disease (PD) and developed dementia according to the Diagnostic and Statistical Manual of Mental Disorders 4th edition (DSM IV) criteria at least 1 year after the onset of motor symptoms (PDD) or met the revised consensus operationalised criteria for DLB. Patients were assigned to a computer-generated randomisation list. All physicians who had contact with patients were masked to treatment allocation. The primary outcome measure was clinical global impression of change (CGIC), which ranged from 1 to 7 points, and a low score means a better outcome. Analysis was by intention to treat based on the last observation carried forward. This trial is registered, number ISRCTN89624516.

FINDINGS: 72 patients with PDD or DLB were randomly assigned and started treatment: 34 with memantine and 38 with placebo. 56 (78%) completed the study. All withdrawals were owing to adverse events, but the proportion of withdrawals was similar in both groups. At week 24 the patients in the memantine group had better CGIC scores than those taking placebo (mean difference 0.7, 95% CI 0.04-1.39; p=0.03). With the exception of improved speed on attentional tasks in the memantine group (a quick test of cognition [AQT] form: difference 12.4, 95% CI 6.0-30.9; p=0.004), there were no significant differences between the groups in secondary outcome measures.

INTERPRETATION: Patients with DLB or PDD might benefit from treatment with memantine, which was well tolerated. Large-scale studies are now required to confirm our preliminary findings.

I believe these just-published results of a 30-week trial to study memantine (Namenda) in DLB and PDD are a follow-up to the study described in the June 2009 post above.

Here's the conclusion of the new study: "The findings inform clinical practice that any possible memantine-associated benefits might be rapidly lost after drug withdrawal. The magnitude of deterioration suggests a symptomatic rather than a disease-modifying effect of the drug."

AbstractOBJECTIVE: This 30-week extension trial was a continuation of the first double-blind randomized controlled trial (RCT) to study memantine in dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD). The objective was to evaluate the presence of recurrence of symptoms upon drug withdrawal. Furthermore, the aim was to explore washout dynamics in order to inform clinical practice.

METHODS: Patients were enrolled from psychiatric, memory and neurological outpatient clinics in Norway, Sweden and the UK. The trial comprised a 4-week washout period and a 26-week open-label treatment period. Outcome measures were presence of recurrence of symptom upon drug withdrawal, Clinical Global Impression of Change (CGIC) and modified motor Unified Parkinson's Disease Rating Scale (UPDRS).

RESULTS: recurrence of symptoms occurred more frequently (p = 0.04) in patients receiving memantine (58%) than in patients receiving placebo (25%). There was a significant global deterioration (p = 0.0003) during washout within the memantine group as measured by CGIC. The patients seemed to recover during the open-label treatment, however these findings were non-significant.

CONCLUSIONS: The findings inform clinical practice that any possible memantine-associated benefits might be rapidly lost after drug withdrawal. The magnitude of deterioration suggests a symptomatic rather than a disease-modifying effect of the drug. Open-label results should merely be considered inspiration for future trials.

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